The present invention relates to determining the quality of oil used in a machine or apparatus.
Oil is used in numerous applications and is commonly used as a lubricant in engines. Due to the broad range of engines and operating environments, lubrication oil is available in a variety of different viscosities (formulations, weights, or grades). For example, lubrication oil could be a single viscosity oil, such as SAE 30 base oil, which has a viscosity of 30 at a set testing temperature or lubrication oil could be a multi-viscosity oil, such as 15W40, 0W30, or 10W30. With multi-viscosity oils, the first number indicates a first viscosity at a first temperature (a cold temp.) and the second number indicates the oil""s second viscosity at a second temperature (a hot temp.) Multi-viscosity oils are beneficial in engine use to help handle the diverse operating environments, such as cold start.
In some devices or engine systems, lubrication oil is also used as an actuation fluid for hydraulically actuated devices. For example, because lubrication oil is a common fluid source in engine systems, it is relatively easy to employ for hydraulic xe2x80x9cmusclexe2x80x9d in hydraulically actuated electronically controlled unit injectors or hydraulically actuated or partially actuated valves. By using hydraulic power, actuation events can be controlled independently of the engine speed (eliminating dependency on the cam shaft) and enhance engine performance. Specifically, in unit injectors, oil is pressurized to relatively high levels and is used in conjunction with an intensifier piston to pressurize fuel to injection pressure. With valves, the pressurized oil can be used to open intake or exhaust valves.
Although lubrication oil is an excellent engine lubricant or actuation fluid, it does have one major drawback, it has a limited life and must be replaced regularly. After prolonged use, the oil can experience viscosity breakdown or can become very dirty and potentially more viscous due to small pieces of metal or dirt getting in the oil. When oil breaks down or becomes dirty, several negatives exist. First, the oil does not provide the desired lubrication and can result in increased engine wear and potentially permanent engine damage. Second, if the oil is being used as an actuation fluid, the oil does not have the anticipated viscosity which results in the oil not responding as expected. Subsequently, this alters the timing, quantity and rate of actuation events, which decreases engine efficiency and may increase emissions.
Therefore, it is beneficial to know when the oil""s quality is unacceptable. Generally, engines or systems do not have any type of oil quality warning device. Instead, it is just recommended that the oil be changed every so often, even thought the actual oil quality is not known. This can result in lost use of good oil or the over use of bad oil.
There have been many different methods developed to try and determine the quality of oil in an engine or system; however, they do not capitalize on existing hardware of system operation and often require additional hardware and housings or cavities in an already complicated engine system. For example in U.S. Pat. No. 6,050,130, issued to Kramer, an additional housing is installed in a pneumatic brake system having a supply of air contaminated with oil. The surface of the housing accumulates a film of oil and an additional sensor directs an electromagnetic waves against the surface of the housing. The sensor then receives a reflected wave back from the surface and produces an oil contamination signal based upon the altered characteristics of the reflected wave.
The present invention is intended to address one or more of the above problems.
In the first embodiment of the present invention, a method for determining oil quality comprises measuring a temperature and oil supply, measuring a pressure in the oil supply and determining the oil quality in response to the measuring steps.
In the second embodiment of the present invention, a system for determining an oil quality comprises a temperature sensor, a pressure sensor and an electronic control module connected to the sensors, wherein the electronic control unit receives a signal from the sensors and determines the oil quality in response to those signals.
In the third embodiment of the present invention, a method for determining oil quality comprises determining an oil grade of the oil supply, measuring the temperature of the oil supply, measuring first pressure of the oil supply, measuring a duration of an event drawing oil from the oil supply, measuring a second pressure of the oil supply, estimating a pressure drop of the oil supply, determining an actual pressure drop of the oil supply in response to measuring the first and second pressures, comparing the actual pressure drop to the estimated pressure drop, and determining an oil quality in response to a comparing step.
In the forth embodiment of the present invention, a method for determining oil quality comprises determining a pressure drop in an oil supply, determining temperature in an oil supply and determining oil quality in response to the determining steps.